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Abstract Essential oils confer protection to plants, and due to their natural origin, there is great interest in their use as antimicrobials. This work aimed to determine the chemical composition, antimicrobial activity and mechanism of action of essential oil from pink pepper (PPEO), against foodborne pathogens. Eighteen compounds (4 monoterpenes and 14 sesquiterpenes) were detected by chromatographic analysis, of which β-myrcene (41%), β-cuvebene (12%) and limonene (9%) were the major compounds. In regards to antimicrobial activity by diffusion in agar and broth, action was verified against two Gram-positive bacteria. Staphylococcus aureus and Listeria monocytogenes presented minimum inhibitory concentration (MIC) of 0.68 and 1.36 mg/mL, respectively. The minimum bactericidal concentration (MBC) was 2.72 mg/mL for both bacteria. The micro-atmosphere diffusion assay demonstrated that the PPEO reduced the development of Escherichia coli and Salmonella Typhimurium, by up to 16 and 15%, respectively. The contact time required for MBC to act effectively on Gram-positive bacteria was less than 12 h, and Gram-negative bacteria were not inhibited, but their growth was significantly reduced by PPEO action. In addition, changes in the permeability and integrity of the cell membrane of all evaluated bacteria were observed, indicating that cell wall damage is one of their mechanisms of action. Highlights • Pink pepper EO (PPEO) is constituted mainly of β-myrcene (41%). • PPEO was tested in different media (solid, liquid and vapor phase). • Gram-positive bacteria were eliminated after 12 h of contact with PPEO. • PPEO promoted cell damage in all tested bacteria. • PPEO promotes the leakage of small ions and macromolecules from bacterial cells. [ABSTRACT FROM AUTHOR]

The natural antimicrobial substance from Lactobacillus paracasei subsp. tolerans FX-6 was found containing novel bacteriocin with broad-spectrum antimicrobial activity to inhibit fungi and bacteria in our previous research. In present study, the biopreservative effect of the antimicrobial substance on quality and shelf life of fresh pork stored for 16 days at 4 °C were investigated based on the microbial (total viable counts), chemical (TVB-N, pH), and sensory evaluation. The five treatments evaluated included a control (sterile distilled water), 0.5% potassium sorbate solution and three levels of antimicrobial substance solution (0.15%, 0.6% and 1.2%). The antimicrobial substance could retain the good quality and extend the shelf life pork during storage and 1.2% antimicrobial substance could extend the shelf life to 12 days and the meat showed good characteristics. These results indicate that the antimicrobial substance has great potential as a natural biopreservative in chilled pork. [ABSTRACT FROM AUTHOR]

Moulds are the most common cheese spoilage organisms which can lead to economic loss as well as raising public health concerns due to the production of mycotoxins. In this study, 897 lactic acid bacteria (LAB) isolated from different herbs, fruits and vegetables were screened for their antifungal activity in an agar plate overlay assay. Thirty-six isolates had weak activity, 11 had moderate activity and 12 were confirmed as having strong activity. The strong antifungal isolates were obtained from a range of different sources but were all identified by 16S rDNA sequencing as being Lactobacillus plantarum. The antifungal spectra for these 12 isolates were determined against eight other moulds commonly associated with cheese spoilage and all isolates were found to possess inhibition against Penicillium solitum, Aspergillus versicolor and Cladosporium herbarum, but not against Penicillium roqueforti, Penicillium glabrum, Mucor circinelloides, Geotrichum candidum or Byssochlamys nivea. The absence of sodium acetate from MRS agar resulted in no inhibition of Penicilium commune, suggesting the synergistic effect of acetic acid with the antifungal LAB, similarly to that previously reported. To determine their potential as biopreservatives in cheese, LAB isolates were inoculated into cottage cheese prior to the addition of P. commune. All Lb. plantarum isolates were found to prevent the visible growth of P. commune on cottage cheese by between 14 and >25 days longer than cottage cheese that contained either no added LAB or LAB that did not have antifungal activity (Lactococcus lactis, Weissella soli, Leuconostoc inhae and Leuconostoc mesenteroides isolates). The results of this study shows that LAB isolated from various herbs, fruits and vegetables possess antifungal activity and have potential for use as biopreservatives in cheese. [ABSTRACT FROM AUTHOR]

Abstract: A novel bacteriocin, sakacin LSJ618, produced by the strain Lactobacillus sakei LSJ618 isolated from traditional Chinese fermented radish, was studied. L. sakei LSJ618 was identified by both phenotypical and physiological tests combined with 16S rDNA sequence analysis. Sakacin LSJ618 is sensitive to hydrolytic enzymes including lipase, is stable between pH 2–8, and is heat resistant (30 min at 121 °C). Sakacin LSJ618 exhibits inhibitory activity against food-spoiling bacteria and food-borne pathogens, including the Gram-positive Listeria monocytogenes, Staphylococcus aureus, Sarcina sp., Micrococcus luteus, and the Gram-negative Proteus sp. and Escherichia coli, but not against most of the lactic acid bacteria tested. Maximal production of bacteriocin was reached in the late stationary phase, and inhibitory activity declined within 26 h. The mode of action of sakacin LSJ618 was determined to be bactericidal, as evidenced by its action upon Micrococcus tetragenus. After partial purification by ammonium sulfate precipitation and Sephadex G-25 chromatography, the molecular weight of sakacin LSJ618 was determined to be 5.2 kDa by Tricine-SDS-PAGE. The identified properties of sakacin LSJ618 indicate that it is a novel bacteriocin with potential application as a biopreservative in the food industry. [Copyright &y& Elsevier]

Abstract: Pentocin 31-1 was produced by Lactobacillus pentosus 31-1, isolated from the traditional China fermented Xuan-Wei Ham. In this work, study on its application as biopreservative in chill-stored nonvacuum-tray-packaged pork meat was carried out. Pentocin 31-1 was prepared by pH-adsorption in 5l stainless steel fermentor. Each 200ml semi-purified bacteriocin was obtained from one fermentation, and the specific activity was 1280AU/ml. The effects of pentocin 31-1 on microbiological counts, physicochemical change and sensory quality of chilled pork in the period of preservation at 4°C was investigated. Results showed that pentocin 31-1 could substantially inhibit the accumulation of VBN and generally suppress the growth of microflora, especially Listeria and Pseudomonas, during chilled pork storage. Microbiological counts, physicochemical parameters and sensory characteristics of the treatments (40AU/ml pentocin 31-1 or 75AU/ml nisin) had exceeded the limitation of Chinese hygienic standard for fresh meat of livestock by day 15. 80AU/ml pentocin could extend the shelf life to 15days and the meat showed good sensory characteristics. These results suggest the potential of pentocin 31-1 as a biopreservative in tray-packaged chilled pork storage. [Copyright &y& Elsevier]

In recent years, bacteriocins have attracted considerable interest for use as natural food preservatives against spoilage and pathogenic microorganisms. Recent studies have shown that the strains of Bacillus cereus group produce a range of highly diverse bacteriocins. In this study, we screened a large number of Bacillus cereus group strains and isolated one strain, Bacillus sp. Xin1, with antimicrobial activity against several food-borne pathogens. A novel circular bacteriocin, bacicyclicin XIN-1 (MW: 5848.1719 Da), was purified from the culture supernatant of Bacillus sp. Xin1. This bacteriocin exhibited high thermal stability, wide pH tolerance, and a wide range of antimicrobial activities against Bacillus cereus , Listeria monocytogenes , and Staphylococcus aureus , three important foodborne pathogens, as well as other pathogens. Bacicyclicin XIN-1 also inhibited the outgrowth of Bacillus cereus spores and did not show hemolysis activity. Bacicyclicin XIN-1 effectively inhibited or eliminated B. cereus ATTCC14579, S. aureus ATCC6538, and L. monocytogenes LM201 in skim milk. Our findings indicate that bacicyclicin XIN-1 has a remarkable potential for use as a natural food preservative in the food industry. • Bacillus sp. Xin1 produces a novel circular bacteriocin, bacicyclicin XIN-1. • Bacicyclicin XIN-1 exhibited high pH and thermal stability. • Bacicyclicin XIN-1 showed a wide range of antimicrobial activity. • Bacicyclicin XIN-1 inhibited the outgrowth of Bacillus cereus spores. • Bacicyclicin XIN-1 showed good effect against three foodborne pathogens in skim milk. [ABSTRACT FROM AUTHOR]